There is a problem in that in interconnect substrates to which an electronic element is mounted, noise generated from the electronic element is electrically connected to an electronic element, flows to a plane separated in an island shape, and thus electromagnetic leakage is increased due to an operation similar to a patch antenna using the noise as a vibration source.
In addition, similarly, there is a problem in that in interconnect substrates to which an electronic element is mounted, a slit formed between a plane which is electrically connected to the electronic element and is separated in an island shape and a plane adjacent thereto uses noise, generated in the electronic element and flowing to the plane separated in an island shape, as a vibration source, and thus electromagnetic leakage is increased due to an operation similar to a slot antenna.
A technique of Patent Document 1 discloses that a high-frequency current changes to a node and a voltage changes to an antinode at the end of an insular power plane in resonance, and leakage from the end is suppressed by connecting insular power planes adjacent to each other through a capacitive member, and causing a high-frequency current to pass through the capacitive member.
A technique of Patent Document 2 discloses that electromagnetic leakage is suppressed by connecting an insular power plane and a power plane adjacent thereto through a plurality of line elements having different lengths or relative dielectric constants, and applying a power supply voltage fluctuation, causing noise leakage, to a plane which is not isolated by phase shift from an isolated power plane.